1. Field of the Invention
This invention relates to a resin composition having excellent moldability, of which a resultant molded product has excellent heat resistance, rigidity and impact resistance.
2. Background Information
Polyamide resins have been widely utilized as molding materials for parts of automobiles or electrical parts, because their molded products have excellent mechanical properties.
However, when applied as the material for parts, etc. to be used under the conditions where excessive external force or heat is applied, they are not necessarily satisfactory with respect to rigidity, impact resistance and heat resistance under the present situation.
Also, there have been developed various resin compositions in which polyamides and polyphenylene ethers are combined. Generally speaking, polyamides are excellent in abrasion resistance, impact resistance, moldability, chemical resistance and mechanical strength, but involve problems in that rigidity may be lowered or dimensional change may occur during water absorption. On the other hand, polyphenylene ethers are excellent in heat resistance and water resistance, with dimensional change being also small, but involve problems in that moldability, chemical resistance and impact resistance are not sufficient.
Accordingly, for the purpose of making avail of mutual advantages and compensating for shortcomings by combining polyamides with polyphenylene ethers, various investigations have been made as described below.
The composition comprising a polyamide and a polyphenylene ether disclosed in Japanese patent publication Nos. 997/1970 and 41663/1984 is improved in flowability, but still insufficient in impact resistance.
The copolymer of a polyamide, a polyphenylene ether and a specific compound as represented by maleic anhydride prepared according to the method disclosed in Japanese patent publication No. 11966/1985, since it is prepared by adding the specific compound during melting and kneading of the polyamide and the polyphenylene ether, is improved somewhat in impact resistance, but not sufficiently, and heat resistance is still insufficient.
The composition comprising a polyamide and a modified polyphenylene ether disclosed in Japanese unexamined patent publication No. 66452/1984 is insufficient in both impact resistance and heat resistance.
The composition comprising a highly amino-rich polyamide, a polyphenylene ether and a specific compound as represented by maleic anhydride disclosed in Japanese unexamined patent pubication No. 250050/1987 is insufficient in impact resistance.
Japanese unexamined patent publication No. 10656/1988 discloses a commposition comprising an A-B-A' type block copolymer and a hydrogenated A-B-A' type block copolymer formulated as the impact resistance improving material into a modified polyphenylene ether and a polyamide. This composition is improved in impact resistance, but it is still insufficient.
As described above, in the resin composition containing a polyamide and a polyphenylene ether as the essential components of the prior art, there has been developed no composition which satisfies all the characteristics of heat resistance, impact resistance and rigidity. Particularly, when the case of using the above resin composition as the material for the outer plate of an automobile, etc. is considered, it is demanded that no deformation should occur even at high temperature during coating baking, and yet plane impact resistance under low temperature in cold districts should be high. Thus, it has been strongly desired to develop a material satisfying such characteristics.